“Run as administrator” starts a program with elevated privileges in the operating system. On Windows, that means the app gets access to system-level actions that normal user programs are blocked from doing.

Typical things an administrator-level app can do:

Install or remove software
Change system settings
Write to protected folders like C:\Windows or Program Files
Modify drivers or services
Change firewall, network, or security settings
Access files belonging to other users
Edit the Windows registry in protected areas

When you use “Run as administrator,” Windows usually shows a User Account Control (UAC) prompt asking for permission.